To analyze shopping behaviors, it may be useful to track the viewpoint of a shopper during a shopping trip. One prior device for recording a viewpoint of the user includes a first camera attached to eyeglasses and configured to capture images the user is looking at, as well as a second camera also mounted on the eyeglasses and oriented towards the user's eyes, which uses corneal reflections to detect the exact focal point of the irises of the shopper's eyes. Using input from the second camera, a cursor is laid on video captured by the first camera, which represents the user's actual eye focal point and movements over time. This prior system suffers from the drawback that it is expensive, generates a large amount of video data, and relies on corneal reflections that can produce inconsistent results, and thus is not suitable for researching the behavior of shoppers, particularly in large scale studies with a large numbers of subjects. This prior system can also require a significant amount of calibration. In addition, the system requires shoppers to wear a specialized pair of eyeglasses, which can be undesirable for some shoppers. In some settings this prior system can be unacceptable to many shoppers simply on “fashion” grounds alone. Another drawback of this approach is that it requires an accurate measurement of average focal distance in order to obtain substantially error-free measurements. This is often difficult in a retail shopping environment, since the average focus may change based on the path that a shopper travels through the environment, and their varying distance from fixtures.